Dynamometer apparatus



DYNAMOMETER APPARATUS Filed April 28, 1951 3 Sheets-Sheet l Fig. 6

w- 5* LL 07 m N a] j INVENTOR.

ATTORNEY 0.0 Johnson BY L14. Fqgg %(i Nov. 17, 1953 I L. w. FAGG ET' AL 2,659,233

DYNAMOMETER APPARATUS Filed April 28, 1951 s Sheets-Sheet-Z INVENTOR. D. 0 Johnson LW Fagg Fig.7

A T TORNE Y NOV. 17, 1953 w, F Gg ET AL 2,659,233

DYNAMOMETER APPARATUS Filed April 28, 1951 3 Sheets-Sheet 15 --II2 US I (/HI INVEN TOR. D. 0. John son BY LM'. Fagg Fig.

A TTOR/VE Y .stylus.

Patented Nov. 17, 1953 UNITED STATES PATENT OFFICE DYNAMOMETER APPARATUS Leo Wayne Fagg and Douglas 0. Johnson, Tulsa, Okla., assignors to Johnson-Fagg Engineering Company, Tulsa, kla., a partnership Application April 28, 1951, Serial No. 223,610

7 Claims. 1

This invention relates to improvements in force measuring devices, and more particularly, but not byway of limitation, to a mechanical dynamometer for measuring and recording the load characteristics of an oil Well pump polish rod.

This invention contemplates a novel mechanical dynamometer utilizing a bifurcated proving ring "as the force measuring medium. The proving ring is adapted to straddle the polish rod of an oil well pump and is adapted to be placed in compression along one diameter thereof. Two pairs of struts are connected to the proving ring and are arranged along the diameter of the ring under compression to transmit the deflection of the ring to a main lever. The main lever magnifies the deflection of the proving ring, and transmits the magnified deflection to a recording The stylus records the magnified deflection of the proving ring on an indicator card carried by a cylindrical drum adapted to be rotated in timed relation to the movement of the polish rod. A timing bar is also provided to time the cycle of operation of the polish rod through the medium of a separate recording stylus on the indicator card.

An important object of this invention is to provide a practical mechanical dynamometer for measuring the load characteristics of an oil well pump polish rod.

Another object of this invention is to provide a mechanical dynamometer, the sensitivity of which will be essentially unaffected by temperature changes.

Another object of this invention is to provide a dynamometer for measuring the load characteristics of an oil well pump polish rod wherein no slack will occur in the recording linkage at a zero loaded conditionduring a cycle .of the pump operation.

A further object of thisinvention is to provide a dynamometer for use on an il well pump polish .rod which will be unaffected by normal distortions of the polish rod or misalignm n of the walking beam hanger.

A further object of this invention is to provide, a novel holding handle for maintaining a ring type dynamometer in the correct position on a polish rod during all operating conditions.

Another object of this invention is to provide a mechanical dynamometer wherein the magniflcation may beeasily and conveniently changed for varying load conditions.

Another object of this invention is to provide a mechanical dynamometer capable of utilizing various sizes 0f proving rings.

A still further object of this invention is to provide a sensitive yet durable mechanical dynamometer which may be economically manufactured.

Other objects and advantages of the invention will be evident from the following detailed description, read in conjunction with the accompanying drawings, which illustrate my invention.

In the drawings:

Figure 1 is a front elcvational view of a novel dynamometer installed on an oil well pump polish rod.

Figure 2 is a side elevational view of the dynamometer shown in Fig. 1.

Figure 3 is a rear elevational-view of a pair of novel aligning washers.

Figure 4 is a cross-sectional view taken along line 4-4 of Fig. 3.

Figure 5 is a rear elevational view of a pair of novel aligning blocks.

-Figure 6 is a cross-sectional view taken along line 8 6 of Fig. 5.

Figure 7 is a, perspective View of a proving ring and struts therefor.

Figure 8 is a plan view of a novel holding handle partially in section for clarity.

Figure 9 is a Perspective view of the recording mechanism with portions removed.

Figure 10 is a side elevational view of the free end of the main lever.

Figure 1-1 is a plan view of the main stylus supporting mechanism.

Figure 12 is, a horizontal cross-sectional view of the main stylus taken above the main stylus adjusting support.

Figure 13 is a perspective view of the timing mechanism.

Referring to the drawings in detail, and particularly Figures 1 and 2, reference character 2 generally designates a novel d-ynamometer disposed on a polish rod '3 of an oil well pump (not shown). The polish rod -3 is normally reciprocated by a walking beam (not shown) through the medium of a hanger 4. A clamp (not shown) is usually clamped to the rod 3 above the lower member '5 of the hanger to Connect the rod 3 to the hanger.

The dynamometer 2 comprises a housing 6, containing the recording mechanism as will be hereinafter set forth, connected to an elastic bifurcated ring 1. The ring? is usually called a, proving ring and is a device developed by the U. S. Bureau of Standards for calibrating testing machines. The ring I straddles the polish rod 3 and rests on a novel washer 8 (Figs. '3 and 4-). A vshaped groove 9 is provided in the upper surface it of the washer E to assure the correc loading of the ring I as will be hereinafter se forth. A transverse slot I! is also provided i the washer 8 at right angles to the V-shape groove 9 to loosely receive the polish rod The lower surface it of the washer 3 is convex and conforms to a portion of a sphere (not shown) to mate with the spherically shaped upper concave surface l3 of another washer i l. The washer i i rests on the lower member of the hanger t and is provided with a transverse slot E5 to loosely receive the polish rod 3.

A suitable rod clamp I6 (Figs. 1 and 2) is socured to the polish rod 3 in vertical spaced relation to the lower member 5 of the hanger i. A spacer block ll (see also Figs. 5 and 6) is disposed under the rod clamp l6, and has a transverse slot 18 therein to loosely receive the polish rod 3. The spacer block W in turn contacts an aligning block i9 disposed on top of the bifurcated ring '5. A V-shaped groove 29 is provided in the lower surface 2| of the block l9 to assure the load imposed on the polish rod 3 will be transmitted to the ring l along the true vertical diameter (not shown) thereof. A transverse slot 22 is provided in the block !9 at right angles to the V-shaped groove 23 to loosely receive the polish rod 3. The block 59 is connected to the ring 1 by suitable set screws (not shown), and the block H is connected to the block i9 by a plurality of dowel pins (not shown) to prevent any misalignment of the blocks H and i9 on the ring l.

It will be apparent that the load imposed on the polish rod 3, by the weight of the pump rods (not shown) extending down into the well bore (not shown) and the column of oil (not shown) being pumped, will be transmitted to the ring 7 to deflect the ring along the vertical diameter thereof. In the event the lower member 5 of the hanger 5 is not exactly at right angles to the polish rod 3, or the polish rod 3 is slightly bent, the washer 8 will automatically move relative to the washer Hi to assure the imposition of the polish rod load along the vertical diam-- eter of the ring 1. The cooperating spherical surfaces !2 and (3 of the Washers 8 and M respectively, permit free movement of the washer 8 when the ring l is tilted to retain the washer 8 in contact with both halves of the bifurcated r ring 1, thereby assuring a uniform loading of the ring. In addition, the V-shaped groove 9 in the washer 8, cooperating with the V-shaped groove in the block 59, assures the imposition of the load along the vertical diameter of the ring 1.

As previously set forth, the ring 1 is bifurcated, having a vertical slot as (Fig. 7) therein extending through slightly more than one half the diameter of the ring. The surfaces of the ring I at the inner end of the slot 24 are semicircular and are adapted to slidingly contact the polish rod 3 when the ring l is placed thereon to permit slight movement of the ring relative to the polish rod when the ring is compressed. The ring :1 (Fig. 2) is retained in operating position on the polish rod 3 by a novel holding handle indicated generally at 26 and extending through the slot 24.

The handle 26 (Fig. 8) comprises an essentially cylindrical housing 21 having a rectangular shaped flange 28 on one end 29 thereof. A longitudinal bore 32 extends partially through the housing 21 and communicates with the end 29 thereof. A rod 33 having a circumferential projection 3 around a medial portion thereof is reciprocally disposed in the bore 32. A helical spring 35 is disposed around the rod 33 with its opposite ends in contact with the inner end (not shown) of the bore 32 and the projection 3 5. The spring 35 constantly tends to force the rod 33 out of the bore 32 for purposes as will be hereinafter set forth. An apertured nut 3'! is threadedly secured in the bore 32 around the rod 33 and is adapted to contact the projection 3A to prevent complete movement of the rod 3-3 out of the bore 32. A head 38, having tapered side faces 39, is secured on the outer end ii! of the rod 33. An axle ll extends outwardly from each side face 39 of the head 38 to support a roller or wheel 32 adapted to contact the polish rod 3.

To place the handle 2'5 in operation, the rod 33 is turned in the housing 2'! until the head 33 is disposed at right angles to the flange 28, whereupon the handle is inserted in the slot 2 3 of the ring '5 with the wheels 32 in contact with the opposite sides of the polish rod 3 as shown in Fig. 2. The housing 2's is then pushed inwardly against the action of the spring 35 and turned to turn the flange 28 in a horizontal position. When the housing 2 1 is released, the spring forces the housing 2l outwardly until the flanges contact the inner surfaces of the bifurcated ring portions i3 to maintain the ring in assembly on the polish rod 3. In the event the ring '5 is caused to move up or down the polish rod as when the supports for the ring fail for example, the Wheels Q2 merely roll along the polish rod 3 and retain the handle 26 in the correct position to maintain the ring 'i on the polish rod 5. The dynamorneter 2. therefore will not be easily dislodged from the polish rod 3 and broken.

Referring again to Fig. '7, a pair of upper struts id and a pair of lower struts '45 are secured in the ring l along the vertical diameter thereof. The struts G l and i5 are secured to the inner surface of the ring l by suitable set screws (not shown). The forward edge i"! of each of the upper struts all is cut away at E8 to provide a thinned or spring portion 69 in the central portion of the ring "E. A pair of vertically spaced transverse apertures 5! are provided in each strut as below the spring portion 39. The apertures El are disposed slightly to the rear of the vertical diameter (not shown) of the ring I for purposes as will be hereinafter set forth. The

.rear edge 52 of each lower strut G5 is cut away at 53 to provide a spring portion A pair of vertically spaced transverse apertures 55 are also provided in each strut above the spring portion The apertures are disposed forward of the vertical diameter of the ring 7.

The struts M and 55 are connected to a U- shaped extension 58 of a main lever 5'! (Fig. 2). The lever El extends through an aperture 58 (Fig. '7) in the ring E into the recording mechanism housing 6 as will be more fully hereinafter set forth. The U-shaped extension 58 straddles the polish rod 3 and is disposed adjacent the inner sides of the struts and 55. Apertures (not shown) are provided in the U-shaped extension 56 in aligned relationship with the apertures 5! and 55 in the struts i4 and 35 respectively to receive screws 56-3. The screws 59 extend through the U-shaped extension 56 and the respective struts it and 5 and are threadedly secured in apertured plates 59 disposed on the outer sides of U-shaped extension 56.

It will be readily seen that upon compression of the ring I, the struts 44 will be moved downwardly and thestruts 45 will be moved upwardly. However, since the free ends of the struts 44 and 45 are connected to the U-shaped extension 56 to preclude the free ends thereof from moving vertically, the struts will be bent at the spring portions 49 and 54 to pivot the main lever 51 in a clockwise direction (Fig. 2). The struts and '45 are installed in the ring I slightly compressed or preloaded, for purposes as will be hereinafter set forth.

A head 62 (Fig. 9) is provided on the end 63 of the main lever 57 in the housing '6. Three (but not limited thereto) aligning grooves 64 are provided in the top surface of the head 52. An elongated transverse slot 65 (Fig. 10.) is provided in the head 62 to receive a clamping nut 66. A second transverse slot 67 communicates with the slot 65 and is adapted to receive a rearwardly extending flange 68 of a clamping plate 69. The clamping plate 69 is secured to the head 62 by a screw 79 cooperating with the clamping nut 66. It will be apparent that the transverse position of the clamping plate 69 may be varied as desired by simply loosening the screw 19 and sliding the nut 66 in the slot 65 While simultaneously moving the plate 69. The flange 68 cooperating with the slot 61 precludes a turning movement of the plate 69 on the head 62. .An aligning groove 1| (Fig. 9) is provided on the top surface of the plate 69 to cooperate with the aligning grooves 64 in positioning the plate 69 as will be more fully hereinafter set forth.

A thin fiexure member I2 (Fig. 9) is secured to the plate 69 adjacent one side marginal edge 14 thereof. The fiexure member 12 extends downwardly from the clamp 69 and is connected at its lower end to a connecting rod clamp I6. A vertical bore (not shown) is provided in the connecting rod clamp 16 to receive the upper end '58 of a connecting rod 99. The rod 89 is adjustably secured in the clamp 16 by a pair of set screws 92.

The lower end (not shown) of the connecting rod 89 is threadedly secured in a wrist connector 89 (see also Fig. 11). The wrist connector 83 is rotatably disposed on a pin 84 carried in the bifurcated end 85 of a magnification arm 86. Three (but not limited thereto) apertures 88 are provided in spaced relation in the magnification arm 86 to selectively receive a screw 99 for connecting the magnification arm 86 to a main stylus pivot support 9!. A transversely extending arm 92 is provided on one end 93 of the support 9|, and a circular shaped head 94 is provided on the opposite end 95 thereof. The support 9| is pivotally supported by a pair of pivot screws 96 engaging the arm 92 and the head 94. The pivot screws 96 are threadedly secured in a pair of longitudinally spaced arms 97 of a main stylus base support 99, in aligned relationship with thescrew 99. A circular shaped head 9-9 is provided on the rear end I99 of the base support 98. The head 99 is suitably secured to the instrument housing 9 to support the base support 98 in a horizontal position. A shaft I9I extends outwardly from the circular head 94 of the pivot support 9| in alignment with the pivot screws .96 tomsupport a main stylus, indicated generally at I The main stylus I92 (Fig. 9) comprises a base portion i 93 having an aperture I94 therein to re,-

ceive the shaft I9I. An arcuate slot I is provided in the base portion. I93 above the aperture I94 and an arcuate slot I96 is provided below the aperture I94. The slots I95 and I69 are formed on the arc of a circle (not shown) having its center line in the center line of the aperture I94. Screws I91 extend through the slots I95 and I96 into the head 94 of the pivot support 9| to secure the main stylus I92 thereto. It will be apparent that the main stylus I92 may be turned to various angular positions on the shaft |9I upon loosening the screws I97. An adjustment support I98 is secured to the upper endI99 of the base portion I93. As clearly shown in Fig. 12., the upper end I09 of the .base portion I93 is cut away at H9 and the adjustment support =|98 is cut away at III to permit securing a thin flexure member II2 between the base portion I93 and the adjustment support I98. The main stylus arm H3 is secured to one side of the flexure member I I2 by a screw II4. A pad H5 is provided on the opposite side of the flexure member I I2 to. receive the screw i I4. The lower end of the main stylus arm II3 extends below the fiexure member I I2 and has a slot (not shown) therein to receive the lower end of a leaf type tension spring H8. The upper end of the spring I I8 is secured by a screw I29 to the adjustment support I08. A set screw I22 is also secured in the adjustment support I98 in contact with the spring [I8 and is utilized to vary the tension of the spring I I8 as will be hereinafter set forth.

A pointer I 23 is secured in the upper end I24of the stylus arm II 3 to record the movement of the main stylus I92 on an indicator card I25. The indicator card I25 is mountedon a drum I26 adapted to be driven through a system of reduc tion gearing not shown) by a pulley I21 (Fig. 1) in the usual manner. A cord I28 is wrapped around the pulley I21 a plurality of times and may be secured to the well head (not shown) to cause rotation of the drum I26 during operation of the polish rod 3. A magnet I29 is secured to the free end of the cord I28 to facilitate the conneotion of the cord to the well head. During inoperation of the dynamometer 2; the cord I28 may be wound on the pulley I21 and the magnet I29conveniently placed in contact with the blocks I! and I9. A guide I39 is secured to the housing 6 to assure uniform winding of the cord I28 on the pulley I21 during operation of the dynamometer 2.

A suitable bracket I3I (Fig. 9) is secured to one side I32 of the housing 6 to support a base stylus I33 therein. The base stylus I33 extends upwardly from the bracket I3I to a position ad.- jacent the drum I26. .A pointer I34 is carried in the upper end I35 of the stylus I33 and is adapted to marl; a base line (not shown) on the card I25 upon rotation of they drum I26 for purposes as will be hereinafter set forth. The stylus I33 is resilient to permit slight bending thereof without damage. A set screw I36 is carried by the bracket I3I in contact with the stylus I33 to vary the tension thereof and hence the pressure exerted by the pointer I34 on the indicator card I25.

A timing mechanism (Figs. 1, 2, and 13) indicated generally at I49 is disposed in the housing 6 adjacent the main stylus I92. The timer I49 comprises a base support i 42 (Fig. 13) suitably secured to the back plate of the housing 6. Two sets of cross springs I43 interconnect the base support I42 with a vibrating support I44 in the usual manner. A stylus arm support I45 is provided on the outer end it of the vibrating support IMI to support a resilient stylus arm I41. The stylus arm extends upwardly from the support M5 and has a pointer I48 in the upper end I 59 thereof adapted to contact the indicator card I25. A set screw IE is carried by the support M in contact with the stylus arm I41 to vary the tension thereof and hence the pressure exerted by the pointer M8 on the indicator card I25. A circular shaped head I5! is also provided on the outer end Hit of the vibrating support I44. The head I5I is connected by an extension I52 to a novel timing bar I53. The extension I52 extends through an aperture (not shown) in an inspection door I5 i provided on the lower front portion of the housing 6. A knobbed screw I55 secures the timing bar I53 and the extension I52 to the head I5I.

Two T-shaped grooves I56 are provided in the upper and lower ends I51 and I58 of the timing bar I53. The grooves I56 communicate with the outer face of the bar I53 and are adapted to receive the T-shaped flanges I59 of a pair of weights EGG. The weights I60 are secured to the bar I53 in various positions by set screws IEI. A pair of aligning grooves I62 are provided in each weight 585 adapted to selectively match two sets of aligning grooves I63 and I54; provided on the bar i53. The sets of grooves I63 and IE are provided in spaced relation on the bar I53 and indicate the number of cycles the stylus I47 will vibrate during a unit length of time upon actuation of the bar I53. For example, when the grooves i5? of the weights I69 are placed in line with the grooves I63, and the bar I53 is set into vibration, the stylus arm I I? will vibrate through ten complete cycles in each second until the bar I53 comes to rest. The grooves I66 may indicate seven and one half cycles per second. The indexing of the timing bar I53 eliminates all guesswork in determining the number of cycles the stylus arm Ifiii vibrates per second and reduces the hook-up time required to place the dynamometer 2 in operation. The pointer I48 will obviously produce a wave on the indicator card I25 during vibration of the arm It'I, from which the velocity of the polish rod 3 may be determined.

A stylus lifting bar I65 (Fig. 1) extends through the housing 6, and is journaled (not shown) in the side walls I32 and HH thereof. The lifting bar M55 is disposed adjacent the base stylus arm I33, the main stylus arm I I3 and the timer stylus arm H57, and upon rotation thereof, all of the stylus arms are moved away from the drum I26 to disengage the respective pointers from the recording chart I25. The bar IE5 is operated by a suitable handle ESE disposed on the outside of the housing (3 adjacent the side wall I II thereof. The handle I66 may also be utilized to lock an inspection door IGI provided in the upper portion of the side wall I iI opposite the drum I28. An observation window its is preferably provided in the upper front portion of the housing 6 opposite the drum I26 to permit the operator to observe the action of the recording mechanism.

A mounting block are (Fig. 2) is provided on the upper rear portion of the housing 6 to facilitate the connection of the housing 6 to the ring I. A pair of spaced projections III are provided on the outer tapered surface II2 of the block IIll and are adapted to contact the outer surface of the ring 5. A pair of screws I13 are carried by the block iit between the projections III for connection in the threaded apertures I'M (Fig. 7 provided in the ring I at an angle of approximately forty five degrees. It will be readily apparent that the housing 6 may be secured through the medium of the mounting block 110 to various sizes of proving rings (not shown).

Opemtion In operation of the dynamoineter 2, the mag net I29 is secured to a fixed object such as the well head (not shown) to cause an oscillatory movement of the drum E25 and indicator card I25 in timed relation to the reciprocatory movement of the polish rod 3. As previously set forth, the load imposed on the polish rod 3 is transmitted to the ring l, causing a compression of the ring along the vertical diameter thereof. The deflection of the ring 7 in turn bends the spring portions 49 and 54 of the struts M and 45 respectively, causing a pivotal action of the main lever 51 about the transverse center line (not shown) of the ring I.

The head 62 and clamp 69 (Fig. 9) will therefore be swung in a vertical arc and will be moved a greater distance than the deflection of the ring '1, depending upon the length of the main lever 5?. The movement of the clamp 69 is transmitted through the medium of the i'lexure member I2, rod clamp l8, rod at, wrist connector 83 and pin 245 (see also Fig. 11) to the magnification arm 83. As the clamp 6,9 is moved by the lever 53?, the clamp it obviously does not move in a true vertical direction, however, the rod 35 will bend slightly to coo erate with the flexure member 52, and prevent any stresses being induced in the magnification arm 35. Furthermore, the wrist connector 83 will pivot on the pin i l to ermit free pivotal movement of the magnification arm 86.

The magnification arm 85 provides a further magnification of the deflection of the ring The degree of magnification produced by the arm 86 depends upon which aperture 88 receives the screw 90, as will more fully hereinafter be set forth. Since the magnification arm 86 is secured to the base pivot ti by the screw 9%, the pivot 94 is pivoted on the screws simultaneously with the movement of the arm 86. The main stylus IE2 is thereby pivoted about the center line of the shaft IIiI, causing the pointer I23 to move across the indicator card 525 and scribe a mark thereon. The main stylus 22, it will be noted, provides a still further magnification of the deflection of the ring 7, and the resulting magnified defiection is indicated on the card I25 through the medium of the pointer I23. The mark made by the pointer I 23 during reciprocation of the polish rod 3 and the simultaneous rotation of the drum I26 represents the loads imposed on the polish rod 3 in the form of a closed diagram as is well known in the art.

Oil wells, as it is also well known, are of varying depths, therefore, the loads imposed on the various sucker rods will Vary considerably. The present dynamozneter S: is sufiiciently flexible, that it may be used on oil wells of any depth. Firstly, the ring I may be replaced with another proving ring (not shown) of the desired size. As previously set forth, the instrument housing 6 may be secured to various sizes of proving rings through the medium of the tapered mounting block Ill} and the screws I752. The size of the proving ring 'I obviously determines the size of diagram (not shown) that will be produced on the indicator card I25.

In the event the desired size of diagram is not produced on the card I 25, the magnification of be disposed. In Fig. 9 for example, themark II is aligned with the central mark 5 and the screw 90 is disposed in the central aperture 88. The rod 80 is thereby disposed in a true vertical position when the clamp 59 and the arm 85 are in their normal or zero positions. To decrease the magnification of the deflection of the ring I, and hence produce a smaller diagram on the card I25, the arm 86 is moved to theleft (Fig. 11) until the screw 99 may be disposed in the right hand aperture 88 and the clamp (is is correspondingly moved to the left until the mark II is aligned with the left hand mark 84. The rod 8!! will then again be in a vertical position to eliminate the possibility of dangerous strains being produced in the mechanism. To increase the size of the diagram on the card 625, the arm 86 and clamp 69 are moved to the right (Figs. 9 and 11).

It will be readily apparent that the deflection of the ring I may be magnified to any desired degree. In the commercial device, when the screw 9!] is in the center aperture 88, the total combined magnification produced by the main lever 51, magnification arm 36, and main stylus I62 is approximately one hundred. The main stylus pointer 523 is therefore moved one hundred times as far as the actual deflection of the ring I to produce a relatively large diagram on the chart I25.

The angular position of the main stylus I02 may be varied on the head M of the base pivot BI to vary the zero position of the pointer E23 by loosening the screws IB'I (Fig. 9). In this manner, the diagram produced on the indicator card I25 may be drawn in the desired position. In addition, the force exerted by the pointer I23 on the card I 2 5 may be varied as desired by turning the set screw-I22 (Fig. 12). The set screw I22 varies the tension of the spring I is which in turn controls the force exerted by the main stylus arm H3.

Simultaneous with the reciprocation of the polish rod 3 and rotation of the drum I26, the timing bar I53 (Figs. 1 and 13) is placed in vibration, causing the pointer I it to scribe a time wave (not shown) on the indicator card I25.

.The time wave is utilized to determine the speed of the polish rod 3 and hence the time required for the well pump (not shown) to complete one cycle of operation. This information is in turn utilized to determine the horsepower requirements of the machinery (not shown) operating the well pump (not shown). The timing bar I53, and hence the pointer 558, may be vibrated any desired number of cycles a minute by correctly positioning the weights Ifiil as previously set forth.

The base stylus pointer ltd (Fig. 9) merely scribes a reference line (not shown) on the card I25 to facilitate the positioning of the zero setting of the main stylus N32. The stylus lifting bar I65 (Fig. 1) is utilized to lift the pointers its, 523 and I53 off of the indicator card :25 when the well pump (not shown) is being operated to reach stable conditions. After the pump has been in operation for a short period, for example fifteen minutes, the lifting bar IE5 is turned by use of the handle I56 to free the stylus arms I33, IIS and I41, whereupon the diagram is taken.

As previously set forth, the struts M and 45 are installed in the ring I slightly under compression. Therefore, no slack will occur in the recording linkage during operation, as when the load is completely removed from the ring I. The

-struts 44 and 35 will be constantly retained in 'a slightly bent condition ready to rotate the main lever 51 immediately upon a deflection of the ring I. It will be noted the struts 44 and 45 are connected to the ring I at the point of minimum stress and will not therefore interfere with the calculated deflection of the ring. It will also be noted that the aperture 58 is provided between the bifurcated portions 43 of the ring I, therefore,

the aperture 58 will not weaken the portions of the ring subject to deflections. Furthermore, the aperture 58 severs the central portion of the ring I, i. e. the portion interconnecting the bifurcated portions thereby precluding interference with the deflection of the portions 43. However, the central portion of the ring I does function to retain the portions 43' in assembly and to support the housing 6 as previously set forth.

From the foregoing it is apparent the present invention provides a practical mechanical dynamometer for measuring and recording the load characteristics of an oil well pump polish rod. The sensitivity of the dynamometer will be essentially unaffected by temperature changes and no slack will occur in the recording mechanism at a zero load condition during a cycle of operation. Furthermore, the accuracy of the dy namometer will not be affected by normal distortions of the polish rod or misalignment of the walking beam hanger. The degree of magnification produced by the recording mechanism may be varied as desired and the recording mechanism may be utilizedwith several different sizes of proving rings, thereby rendering the device applicable on any depth of oil wells. It is also apparent that the present invention provides a novel holding handle for a ring type 'dynamometer to effi'oientlyretain the dynamomet'er in operating position on a polish rod.

Changes may be made in the combination and arrangement of parts as heretofore set forth in the specification and shown in the drawings, it being understood that any modification in the precise embodiment of the invention may be made within the scope of the following claims without departing from the spirit of the invention.

We claim:

1. In a dynamometer comprising a bifurcated elastic ring providing two ring portions to receive a compressive force along one diameter thereof, a lever extending into the ring at right angles to the center line of the ring, a pair of struts connected to the inner periphery of each portion. of the ring at substantially diametrically opposed points and extending inwardly in the ring along said one diameter thereof, a thinned portion in each of said struts parallel to the center line of the ring, means for connecting the free ends of said struts in a substantially perpendicular position to the lever to one end of the lever in spaced parallel chordal planes whereby upon compression of the ring the struts are bent at said thinned portions tov pivot the lever about the center line of the ring, and a recording mechanism connected to the opposite end of the lever.

2. In a dynamometer comprising an elastic ring to receive a compressive force along one diameter thereof, a slot in the ring providing two ring portions, a lever extending into the ring opposite the slot at right angles to the center line of the ring, a pair of struts connected to the inner periphery of each ring portion at substantially diametrically opposed points and extending parallel to said one diameter of the ring, a portion of each strut being cut away in a direction parallel to the center line of the ring, the struts disposed in the ring substantially perpendicular to the lever and with the free ends connected to the lever in spaced parallel chordal planes, whereby upon compression of the ring the struts are bent to pivot the lever about the center line of the ring, and a recording mechanism connected to the opposite end of the lever.

3. In a dynamometer for measuring the force imposed on a pump polish rod, comprising a bifurcated elastic ring adapted to straddle the polish rod, a hanger for reciprocating the ring and polish rod, a clamp secured to the polish rod above the ring, a block between the upper surface of the ring and the clamp, a V-shapedcomplementary spherical washer between said washer and the hanger.

4. In a dynamometer for measuring the force imposed on a pump polish rod, comprising a bifurcated elastic ring adapted to straddle the polish rod, a hanger for reciprocating the ring and polish rod, a clamp secured to the polish rod in contact with the ring to transmit the force exerted on the polish rod to the ring, means for recording the deflection of the ring, and a handle for retaining the ring in operating position on the polish rod, said handle comprising a housing, flanges on one end of the housing for gripping the inner surface of the bifurcated portions of the ring, a reciprocable rod in the housing extending toward the polish rod, rollers carried by the rod in contact with the polish rod. and a spring in the housing on the rod for forcing the rollers into contact with the polish rod and the flanges in contact with the ring.

5. In a dynamometer for measuring the force imposed on a pump polish rod, comprising a bifurcated elastic ring adapted to straddle the polish rod, a hanger for reciprocating the ring and polish rod, a clamp secured to the polish rod in contact with the ring to transmit the force exerted on the polish rod to the ring, means for recording the deflection of the ring, and a handle extending through the bifurcated portions of the ring for retaining the ring on the polish rod, said handle comprising a cylindrical housing, flanges on one end of the housing, a reciprocable rod in the housing and extending from said one end thereof, a tapered head on the extended end of the rod, rollers carried by the tapered head, and a spring anchored in the housing and to the rod for forcing the rollers into contact with the polish rod and the flanges into contact with the inner surface of the bifurcated portions of the ring.

6. In a dynamometer for mear-zuring the load characteristics of a pump polish rod, comprising a bifurcated elastic ring adapted to straddle the polish rod, means for transmitting the load of the polish rod to the ring to deflect the ring, an instrument housing, a mounting block on the instrument housing, spaced lugs on the mounting block for contacting the outer periphery of the ring, a screw carried by the mounting block and adapted to enter the ring in a radial direction to force the lugs into contact with the ring and sup port the instrument housing, and recording means in the instrument housing connected to the ring to record the deflection of the ring.

7. In a dynamometer comprising a bifurcated elastic ring providing two ring portions to receive a compressive force along one diameterthereof, a lever extending into the ring portions, a pair of resilient struts disposed in the ring substantially perpendicular to the lever and parallel to one diameter of the ring, said struts connected to the inner periphery of each portion of the ring at substantially diametrically opposed points, the free end of said struts being connected to the end of the lever in spaced parallel chordal planes to pivot the lever upon deflection of the ring, and a recording mechanism connected to the opposite end of the lever.

LEO WAYNE FAGG. DOUGLAS 0. JOHNSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 753,015 Tretch Feb. 23, 190 2,063,169 Kemler Dec. 8, 1936 2,346,281 Templin Apr. 11, 1944 2,522,117 Holt et al Sept. 12, 195i) 

